1. Field of the Invention
The present invention relates to an electric steering apparatus for a vessel propulsion apparatus, and a vessel propulsion apparatus including the electric steering apparatus.
2. Description of the Related Art
U.S. Pat. No. 8,246,400 discloses a plurality of electric steering apparatuses for a vessel propulsion apparatus. Each electric steering apparatus includes a motor that generates a driving force to turn an outboard motor in the left-right direction, and a lock portion that transmits only a driving force transmitted from the upstream side to the downstream side.
The electric steering apparatus shown in FIG. 5 of U.S. Pat. No. 8,246,400 (hereinafter, referred to as “first electric steering apparatus”) includes a lock release mechanism that shuts off a driving force transmission path on the downstream side of the lock portion to disable the lock portion. When a user manually steers the outboard motor, the outboard motor is directly pushed by the user in a state in which the driving force transmission path is shut off.
The electric steering apparatus shown in FIG. 24 of U.S. Pat. No. 8,246,400 (hereinafter, referred to as “second electric steering apparatus”) includes a rotating member that is disposed on the upstream side of the lock portion, and rotates integrally with a rotary shaft of the motor. When a user manually steers the outboard motor, the rotating member is manually rotated by the user in a state in which the driving force transmission path is not shut off. Accordingly, the motor rotates, and the force of the user applied to the rotating member is transmitted to the outboard motor via the transmission path.
In the first electric steering apparatus, in the state in which the driving force transmission path is shut off, the outboard motor is manually steered by a user. Therefore, when the outboard motor is manually steered, only members disposed on the downstream side of the shut-off position move together with the outboard motor. Therefore, the positional relationship between the upstream side of the shut-off position and the downstream side of the shut-off position changes. For example, the relationship between the rotation angle of the motor and the steered angle of the outboard motor changes. Therefore, after this, an operation to restore the changed positional relationship is required.
In the second electric steering apparatus, the rotary shaft of the motor rotates by the same rotation angle as that of the rotating member. The rotation of the motor is decelerated, so that when a user manually steers the outboard motor, the user is required to rotate the rotating member a number of times. Therefore, the steering operation is troublesome, and it takes time to move the outboard motor to an intended steered angle.